I think Greg Ellis should go. He isn't worth 6.25 million against the cap. He is a part time player. He did have 8 sacks, and he played much better after the bye when Terence Newman came back.
However, take a look at his season:
During the first 6 games, Ellis had 2.0 sacks. He tallied them against the Eagles. Then, Ellis went 6 straight games without a sack.
After that six game sackless streak, Ellis tallied 1 sack against the Rams. Then, he went 3 games without one. That is 3 sacks in 9 games.
After the bye, Ellis put up 5 sacks, including 2.5 against the Giants. The Giants lost their RT in that game. That is 5 sacks in 7 games.
I will take my chances with replacing him with a younger player, via the draft or free agency. When you are averaging 10.1 wins a season over the past three years, Ellis is expendable.
Anthony Spencer had 3.0 sacks his rookie year, and he didn't play on third down very much this past year. Plus, he missed four games due to injury. You can't have a steak at every position. The third rusher is important, but not $6.25 million important. Spencer and another player can make up for his sack production.
Spencer should be able to, at least, double the 3.0 sack total of his rookie year. That would be 6 sacks vs Ellis' 8 in 2008.
The time for Anthony Spencer is now. You can't get sacks if you don't play on third down. Spencer had 1.5 sacks. By letting Ellis go, you get rid of a perpetual complainer, and you are putting responsibility on Anthony Spencer. Spencer needs to be challenged, and ditching Ellis will challenge him. He was looking great in camp before he was hurt against a cutblocking team. Ellis' behavior isn't helpful to Spencer or the team. It can be described as selfish.
It is up to Anthony Spencer to grab the opportunity and go. He has to grow up on and off the field. It's time to quit treating him like a baby. The Steelers didn't treat Lamar Woodley like a baby, and they wouldn't keep Ellis around (at a $ 6.25 million dollar price tag) and hold his development back.